Method of fabricating a tape having apertures under a lead frame for conventional IC packages

ABSTRACT

A semiconductor integrated circuit device, and method of manufacturing the same, having a conventional-type lead frame with the die paddle removed. In particular, the die paddle is replaced with a section of tape that is supported by the ends of the lead fingers. The semiconductor die is attached to the tape so that it may be wire bonded to the lead fingers. The tape contains at least one slot to allow for expansion and/or contraction of the tape due to various temperatures experienced during the manufacturing process so that the tape does not wrinkle or warp to alter the position of the die.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/820,999,filed Mar. 29, 2001, now U.S. Pat. 6,518,650, issued Feb. 11, 2003,which is a continuation of application Ser. No. 09/537,134, filed Mar.29, 2000, now U.S. Pat. No. 6,215,177, issued Apr. 10, 2001, which is acontinuation of application Ser. No. 09/038,858, filed Mar. 11, 1998,now U.S. Pat. No. 6,091,133, issued on Jul. 18, 2000, which is acontinuation of application Ser. No. 08/618,359, filed Mar. 19, 1996,now U.S. Pat. No. 5,729,049, issued Mar. 17, 1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to semiconductor integrated circuit(IC) devices and, more specifically, to a method and apparatus for asemiconductor device utilizing a conventional-type lead frame with nodie paddle and having a section of tape to support the semiconductordie.

2. State of the Art

The semiconductor industry has become one of the most competitiveindustries in the world. It is thus essential for manufacturers tominimize the per unit production cost while simultaneously increasingthe number of units manufactured. Because of the high volume ofmanufactured products associated with semiconductor fabrication, smallchanges in production throughput times per semiconductor device can makedramatic changes in the number of devices produced. Moreover, decreasingthe number of defective devices produced, even by a small amount, canhave a similar dramatic effect on the overall production rate.

One method of semiconductor device construction that has been recognizedis to use an adhering member to retain the lead fingers of a lead framehaving a semiconductor support therewith during the wire bondingoperation of leads between the semiconductor device and each leadfinger. Such methods and semiconductor devices are illustrated in U.S.Pat. Nos. 4,835,120, 4,891,687, 5,227,662, 5,352,633, and 5,475,918.

Another method of semiconductor device construction that has beenrecognized is the lead-over-chip (LOC) configuration. In thisconfiguration, the lead frame has no semiconductor paddle support as apart thereof. Rather, the semiconductor device is supported in relationto the lead frame and its lead fingers by means of adhesive tapesecuring the semiconductor device to the lead fingers overlaying thesemiconductor device during wire bonding and other operations. TypicalLOC type methods and semiconductor devices are illustrated in U.S. Pat.Nos. 4,862,245, 5,252,853, 5,304,842, and 5,471,369.

The manufacturing advantages of having a paddleless, conventional-typelead frame have also been recognized in the art. For example, asillustrated in U.S. Pat. No. 5,140,404(“the '404 patent”), assigned tothe assignee of the present invention, the die paddle is replaced withtape. The tape is attached to the undersides of the lead fingers andextends over the portion of the lead frame where the die paddle wouldnormally be located. The tape serves at least two functions. First, itprovides a platform to support the semiconductor die, and second, itstabilizes the ends of the lead fingers during the wire bondingoperation. Moreover, because the tape is attached to one side of thelead frame, it provides substantially the same downset to lower the dierelative to the top surface of the lead fingers. Thus, the semiconductordie is attached to and supported by the tape during wire bonding of thecontacts of the die to the lead fingers.

However, rather than use thermosetting adhesives to attach the leadfingers of the lead frame to the tape and the semiconductor device, asin the process illustrated in the '404 patent, one or more thermoplasticlayers are applied to a tape which is subsequently used to support thesemiconductor device in a conventional-type lead frame having nosemiconductor support paddle therewith. The lead fingers of the leadframe are bonded to the semiconductor device during the wire bondingoperation. Use of one or more thermoplastic layers on a tape to supportthe semiconductor device, as well as to lock the lead fingers of thelead frame in place, is used in place of typical adhesives which requiresubsequent oven curing steps, such use of thermoplastic layers requiresthe substantially simultaneous bonding of both the semiconductor deviceand the lead fingers of the lead frame to the tape while thethermoplastic remains in its soft state. Furthermore, since thethermoplastic typically melts at 100 degrees Centigrade and the wirebonding of the lead fingers to the semiconductor device occurs when bothare heated to approximately 250 degrees Centigrade, the thermoplasticmay soften during the wire bonding process, thereby allowing thesemiconductor device and/or lead fingers to move, causing bondingproblems.

When the lead frame is being manufactured, if the lead fingers of a leadframe have been locked in place through the use of thermosetting typesof adhesives, rather than thermoplastic types of adhesive as describedin the '404 patent, subsequently, it is easier to use a thermosettingtype of adhesive to attach the semiconductor device on the tape in thepaddleless lead frame as conventional semiconductor processing iscapable of such adhesive use and curing without modification to thefabrication process.

From the foregoing, while it has been recognized in the art to increasechip production efficiency while simultaneously decreasing the number ofdefective products, it is desirable to utilize a conventional-type leadframe without a die paddle and use tape to retain the chip in the leadframe, as well as to retain the lead fingers of the lead frame duringwire bonding operations.

In a conventional-type lead frame, the lead fingers, which form theleads of the packaged semiconductor device, inwardly extend toward thecenter of the lead frame. A die paddle is positioned proximate the tipsor proximal ends of the lead fingers and is generally rectangular inshape. The die paddle provides a relatively stable base to mount thesemiconductor die and keep the semiconductor die in place during variousmanufacturing operations where die alignment is crucial, such as wirebonding.

The die paddle is typically positioned on a lower plane than the planedefined by the lead fingers such that when the semiconductor die isattached to the die paddle in this configuration, the lowered die paddledecreases the angle and length of wire necessary to wire bond thecontacts of the semiconductor die to the ends of the lead fingers.Having the die paddle on a lower plane is more difficult to manufactureand may create various handling problems during the manufacturingprocess. For example, modified or alternate fixtures for handling leadframes with a lowered die paddle, as opposed to lead frames where thedie paddle is not lowered, may be necessary. Additionally, the ends ofthe lead fingers that are wire bonded are typically plated with gold orsilver. Plating part of the die paddle is also necessary if a down bondis needed to secure the semiconductor die to the die paddle.

During the wire bonding operation, the lead frame, along with itsattached die, is typically placed on a heating block to beat the leadframe and die to a specific temperature. Typically, the heating blockheats the semiconductor device to approximately 250 degrees Centigrade.Accordingly, any type of tape used to support the die to the lead frame,as previously discussed, must be capable of withstanding temperatures ofapproximately 250 degrees Centigrade without melting and/or distortingfrom expansion. If the tape does warp or wrinkle from the heat, thesemiconductor die may move relative to the lead fingers and/or the leadfingers may move relative to the semiconductor die. Any such movementmay cause misalignment of the lead fingers in relation to the diecontacts during the wire bonding operation, resulting in improper wirebonding and production of a defective semiconductor device. Moreover, ifthe wire bonding operation successfully wire bonds each of the diecontacts to the lead fingers, cooling of warped or wrinkled tape maycause the die to pull apart the wire bonds. Thus, it would beadvantageous to provide a tape supported lead frame for die attachmentthat also addresses the effects of expansion and/or contraction of thetape used to support the semiconductor die. It would also beadvantageous to provide a tape supported lead frame for die attachmentthat further addresses the effects of attaching the die through the useof thermosetting adhesives, rather than thermoplastic adhesives whichare soft when the die is attached or may soften during the wire bondingprocess, thereby allowing the die or lead fingers to move with respectto each other.

SUMMARY OF THE INVENTION

According to the present invention, a conventional-type, paddleless leadframe is provided, having at least one piece of tape extending to andbetween the lead fingers where a die paddle would normally lie in aconventional-type lead frame. The tape is of a generally rectangularconfiguration, but may also be in the form of a circle, oval,parallelogram or any other shape that would fit within the footprintdefined by the outside edge of packaging encapsulant. A semiconductordie is then attached to the tape between the proximal ends of the leadfingers using thermosetting types of adhesives. The lead fingers arealso attached to the tape through the use of thermosetting types ofadhesives.

In a preferred embodiment, the piece of tape has at least one slotformed therein to allow the tape to expand and contract as it is heatedand cooled without moving the semiconductor die attached thereto. Also,the slot permits improved adhesion of the lead fingers and thesemiconductor die to the tape during heating and cooling.

In another preferred embodiment, the die supporting tape includes twotransversely extending, substantially parallel slots. The two slotsextend along opposite sides of the tape and are proximate the proximalends of some of the lead fingers. The two slots may also extend alongeither of the two substantially parallel sides of the tape and may havesubstantially squared or curved ends.

In yet another preferred embodiment, the tape includes four slotsforming a crossing pattern. The four slots may be substantially parallelto the sides of the tape or extend substantially diagonally across thetape.

In still another embodiment, the slots are formed from a series ofapertures that may be of varying or substantially similar shapes andsizes. For example, each slot may be formed of a row of substantiallyrectangular or square apertures extending along two or four sides of thetape. Moreover, the apertures may form a grid-like pattern over asubstantial portion of the tape.

In yet another preferred embodiment, the die supporting tape iscomprised of at least two pieces of tape with a slot formed by theseparating distance between the pieces of tape. Each piece of tape mayalso have its own opening or slot formed therein to further allow forexpansion or contraction of the tape.

It is believed that a major aspect of the invention is that the tapeused to support the die can accommodate a certain amount of expansionand/or contraction from heating or cooling by including an aperturetherein without disturbing the alignment of the semiconductor die. Thiscan be accomplished by having an aperture formed into the tape itself orusing a number of pieces of tape with openings formed in between thepieces. These, and other features of the present invention, will becomeapparent from the following detailed description, the accompanyingdrawings, and the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic top view of a semiconductor integrated circuitdevice in accordance with the present invention including a firstembodiment of a tape segment;

FIG. 2 is a schematic side view of the semiconductor integrated circuitdevice of FIG. 1;

FIG. 3 is a close-up partial top view of the lead fingers and tapeconfiguration of FIG. 1 without an associated semiconductor die;

FIG. 4 is a close-up partial top view of a second embodiment of the leadfingers and tape configuration in accordance with the present invention;

FIG. 5 is a close-up partial top view of a third embodiment of the leadfingers and tape configuration in accordance with the present invention;

FIG. 6 is a close-up partial top view of a fourth embodiment of the leadfingers and tape configuration in accordance with the present invention;

FIG. 7 is a close-up partial top view of a fifth embodiment of the leadfingers and tape configuration in accordance with the present invention;

FIG. 8 is a close-up partial top view of a sixth embodiment of the leadfingers and tape configuration in accordance with the present invention;

FIG. 9 is a close-up partial top view of a seventh embodiment of thelead fingers and tape configuration in accordance with the presentinvention;

FIG. 10 is a close-up partial top view of an eighth embodiment of thelead fingers and tape configuration in accordance with the presentinvention; and

FIG. 11 is a close-up partial top view of a ninth embodiment of the leadfingers and tape configuration in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a semiconductor integrated circuit (IC) device 10is shown including a portion of a conventional-type lead frame 12.Typically, the lead frame 12 is part of a lead frame strip comprised ofa plurality of lead frames extending from broken edges 13 and 15 and arerepeated about the slits 17. The lead frame 12 includes a plurality oflead fingers 18 that extends toward the center of the lead frame 12.Each of the lead fingers 18 includes a lead end 20 at a proximal endthat is wire bonded to the semiconductor die 14 by wire bond 22.Typically, the lead ends 20 are plated to achieve a sufficient bondbetween the wire bond 22 and the lead end 20. The plated area isgenerally indicated by dashed line 24.

As should be recognized, the lead frame 12 does not include a die paddlefor supporting the semiconductor die 14. Rather, the semiconductor die14 is supported by tape 16. As better seen in FIG. 2, the tape 16 isattached to the bottom surface 26 of the lead frame 12 preferably usinga thermosetting type of adhesive. When a semiconductor die 14 issubsequently attached to the tape 16, preferably using a thermosettingtype of adhesive, the die 14 sits down inside the lead frame 12. In thismanner, the length of a wire bond 22 between the die 14 and the leadfinger 18 is decreased because the top surface 28 of the die 14 ispositioned closer to the top surface 30 of the lead frame 12, as opposedto a die attached to the top surface of a lead frame having a die paddlethat is not lowered. The preferred type of adhesive used to bond thelead fingers 18 of the lead frame 12 and the semiconductor die 14 to thetape 16 may be selected from the group of epoxies, acrylics, siliconesand polyamides, such adhesives being thermosetting, i.e., capable ofirreversibly polymerizing and setting or hardening when heated to someappropriate temperature. Such adhesives are not a thermoplastic, i.e., amaterial that can be repeatedly melted or softened by heat without achange of properties. When such adhesives are used to bond the leadfingers 18 of the lead frame 12 to the tape 16, since the adhesive mustbe cured, typically in an oven, it is necessary to bond the lead fingers18 to the tape 16 before bonding the semiconductor die 14 to the tape16. In this manner, the lead fingers 18 of the lead frame 12 are fixedor locked in position by the tape 16 with the semiconductor die 14 beingsubsequently locked in position on the tape 16 with respect to the leadfingers 18. While the lead fingers 18 may engage the tape 16 over anydesired length thereof, the tape 16 preferably engages the lead fingers18 over a length of at least 0.005 inches and may be in excess of 0.060inches.

Referring again to FIG. 1, the tape 16 includes two slots 32 and 34transversely extending across the tape 16 proximate a number of leadends 20. As shown, the ends 36 and 38 of the die 14 extend into theslots 32 and 34, respectively. The slots 32 and 34 may, however, beentirely outside or inside the footprint of the die 14. Moreover, theslots 32 and 34 are longer than the corresponding width of the die.However, the slots 32 and 34 may be shorter or longer, depending on thesize of the die used and/or the desires of the manufacturer.

As shown in FIG. 3, the slots 32 and 34 may transverse the short side 40of the tape 16 and have a generally rectangular configuration.Similarly, the slots 42 and 44 shown in FIG. 4 may transverse the longside 46 of the tape 16 and have rounded ends 48, 50 and 52, 54,respectively.

It may, however, not be necessary to incorporate more than one slot inthe tape 16 to achieve the necessary give in the tape 16 to allow forexpansion and/or contraction of the tape 16. For example in FIG. 5, asingle slot 56 may transverse the tape 16 about the center line 58.Moreover, as shown in FIG. 6, the slot or opening 60 may actually beformed by spacing apart two tape segments 62 and 64. In addition, eachsegment of tape 62 and 64 may each include their own transverseapertures 66 and 68, respectively, positioned proximate severalproximate ends 70 of the lead fingers 18.

It may also be desirable to incorporate more than two slots and positionthe slots so that they are not substantially parallel to one another.For example in FIG. 7, the slots 72, 74, 76, and 78 are substantiallydiagonally positioned across the tape 16 to form an “X” pattern.Likewise, the slots 80, 82, 84, and 86 may form a cross-like pattern inthe tape 16, as shown in FIG. 8.

Referring now to FIG. 9, each slot may be formed from a plurality ofapertures 88 positioned to form any of the previously describedconfigurations or any other configuration as desired. In thisembodiment, the apertures are configured similar to the embodiment shownin FIG. 3, but may be altered in size, shape, and/or number.

As shown in FIG. 10, the apertures may include both relatively smallerapertures 90 and larger apertures 92 and may be positioned proximate theperimeter 94 of the tape 16.

Finally, as shown in FIG. 11, it may be desirable to form a grid-likepattern of slots or apertures 96 over a substantial portion of the tape16. The apertures 96 may be all substantially the same size or varyingin size as illustrated.

In the exemplary embodiments, the tape as illustrated has a generallyrectangular configuration, and the illustrated slot configurations aregenerally symmetrical about one lead frame axis or another. Thoseskilled in the art, however, will appreciate that the size and/or shapeof the tape may vary and the slots may equally be asymmetricallypositioned about the tape without departing from the spirit of thepresent invention. It will also be appreciated by one of ordinary skillin the art that one or more features of the illustrated embodiments maybe combined with one or more features from another to form yet anothercombination within the scope of the invention as described and claimedherein. Thus, while certain representative embodiments and details havebeen shown for purposes of illustrating the invention, it will beapparent to those skilled in the art that various changes in theinvention disclosed herein may be made without departing from the scopeof the invention, which is defined in the appended claims. For example,various slot configurations may be utilized; the number of apertures maybe increased or decreased; and the number of tape segments may bevaried.

1. A method of assembling a semiconductor device and a lead frame, thelead frame having a plurality of lead fingers in strip form, each leadfinger of the plurality of lead fingers having a bonding end, theplurality of lead fingers forming an opening for a semiconductor device,the lead frame having no die paddle for supporting the semiconductordevice thereon, comprising: attaching a segment of tape to portions ofthe lead frame, the segment of tape extending across the opening havingadhesive located thereon forming attachment locations for thesemiconductor device and for portions of the plurality of lead fingersof the lead frame, the segment of tape having an aperture therein forcompensating for expansion and contraction of the segment of tape;attaching portions of lead fingers of the plurality of lead fingers to aportion of the segment of tape; and attaching the semiconductor deviceto at least a portion of the segment of tape at the attachment locationfor the semiconductor device using the adhesive located on a portion ofthe segment of tape, the semiconductor device having a portion thereoflocated within the opening formed by the plurality of lead fingers ofthe lead frame.
 2. The method of claim 1, further including: forminganother aperture in the segment of tape.
 3. The method of claim 2,wherein the semiconductor device is attached to the segment of tape suchthat at least a portion of an outer periphery of the semiconductordevice is adjacent to a portion of a periphery of the at least oneaperture.
 4. The method of claim 1, further including: forming aplurality of apertures in the segment of tape.
 5. The method of claim 4,wherein the plurality of apertures substantially forms a grid-likepattern of apertures.
 6. The method of claim 4, wherein thesemiconductor device is attached to the segment of tape such that atleast a portion of an outer periphery of an attachment surface of thesemiconductor device is positioned within at least one aperture of theplurality of apertures.
 7. The method of claim 1, further including:wire bonding contacts of the semiconductor device to the bonding ends ofthe plurality of lead fingers.
 8. The method of claim 1, furtherincluding: packaging the semiconductor device in an encapsulatingmaterial to form a packaged semiconductor device.
 9. The method of claim8, further comprising: forming the segment of tape to fit within theencapsulating material.
 10. A method of assembling a semiconductordevice and a lead frame, the lead frame having a plurality of leadfingers, each lead finger of the plurality of lead fingers having an endforming an opening between the ends of the plurality of lead fingers ofthe lead frame having a size of at least an attachment surface of thesemiconductor device, comprising: attaching at least two tape segmentsto portions of the lead frame, the at least two tape segments beingspaced to define at least one opening between the at least two tapesegments providing an attachment location for the semiconductor devicetherein and portions of the plurality of lead fingers of the lead framethereto, the at least two tape segments shaped for extending across theat least one opening forming the attachment surface of the semiconductordevice, each segment of tape having at least one aperture therein toallow for the expansion and contraction thereof.
 11. The method of claim10, further including forming a plurality of apertures in at least onetape segment of the at least two tape segments.
 12. The method of claim11, wherein the plurality of apertures substantially forms a grid-likepattern of apertures.
 13. The method of claim 11, further including:attaching the semiconductor device to the at least one tape segment ofthe at least two tape segments having at least a portion of an outerperiphery of the semiconductor device adjacent to a periphery of atleast one aperture of the plurality of apertures.
 14. The method ofclaim 13, wherein the semiconductor device is attached to the at leastone tape segment such that at least a portion of the outer periphery ofthe semiconductor device is positioned within the at least one apertureof the plurality of apertures.
 15. The method of claim 13, furtherincluding: wire bonding contacts of the semiconductor device to the endsof the plurality of lead fingers.
 16. The method of claim 10, furtherincluding: packaging the semiconductor device in an encapsulatingmaterial to form a packaged semiconductor integrated circuit device. 17.The method of claim 16, further comprising forming the at least two tapesegments to fit within the encapsulating material.
 18. The method ofclaim 10, wherein the at least two tape segments comprises three or moretape segments.
 19. The method of claim 10, further including forming atleast one aperture in at least one tape segment of the at least two tapesegments.
 20. The method of claim 10, wherein the adhesively attachingthe at least two tape segments to the portion of the ends of theplurality of lead fingers comprises spacing the at least two tapesegments to define at least two openings between the at least two tapesegments.
 21. An method for attaching a semiconductor device to a leadframe, the lead frame having a plurality of lead fingers, each leadfinger having an end forming an opening for a semiconductor device to bemounted therein, comprising: attaching a segment of tape to portions ofthe lead fingers of the lead frame, the segment of tape having athermosetting adhesive located on a portion thereof for forming anattachment location for the semiconductor device thereon within the endsof plurality of lead fingers, the segment of tape having an aperturetherein for allowing movement of portions of the segment of tape; andattaching the semiconductor device to at least a portion of the segmentof tape at the attachment location for the semiconductor device, thesemiconductor device being supported by the segment of tape.
 22. Themethod of claim 20, further including: forming another aperture in thesegment of tape.
 23. The method of claim 20, further including: forminga plurality of apertures in the segment of tape.
 24. The method of claim23, wherein the plurality of apertures substantially forms a grid-likepattern of apertures.
 25. The method of claim 22, wherein thesemiconductor device is attached to the segment of tape such that atleast a portion of an outer periphery of the semiconductor device isadjacent to a portion of a periphery of the at least one aperture. 26.The method of claim 23, wherein the semiconductor device is attached tothe segment of tape such that at least a portion of an outer peripheryof the attachment surface of the semiconductor device is positionedwithin at least one aperture of the plurality of apertures.
 27. Themethod of claim 20, further including: wire bonding contacts of thesemiconductor device to the plurality of lead fingers.
 28. The method ofclaim 20, further including: packaging the semiconductor device in anencapsulating material to form a packaged semiconductor device.
 29. Themethod of claim 27, further comprising: forming the segment of tape tofit within the encapsulating material.
 30. A method of attaching asemiconductor device to a lead frame, the lead frame having a pluralityof lead fingers, each lead finger having an end forming an openingbetween the ends of the plurality of lead fingers of the lead framehaving a size of at least an attachment surface of the semiconductordevice, comprising: attaching at least two tape segments to portions ofthe lead fingers of the lead frame, the at least two tape segments beingspaced to define at least one opening between the at least two tapesegments providing an attachment location for the semiconductor devicetherein, each segment of tape having at least one aperture therein toallow for movement of portions of the at least two tape segments. 31.The method of claim 30, further including forming a plurality ofapertures in at least one tape segment of the at least two tapesegments.
 32. The method of claim 31, wherein the plurality of aperturessubstantially forms a grid-like pattern of apertures.
 33. The method ofclaim 31, further including: attaching the semiconductor device to theat least one tape segment of the at least two tape segments having atleast a portion of an outer periphery of the semiconductor deviceadjacent to a periphery of at least one aperture of the plurality ofapertures.
 34. The method of claim 33, wherein the semiconductor deviceis attached to the at least one tape segment such that at least aportion of the outer periphery of the semiconductor device is positionedwithin the at least one aperture of the plurality of apertures.
 35. Themethod of claim 33, further including: wire bonding contacts of thesemiconductor device to the ends of the plurality of lead fingers. 36.The method of claim 30, further including: packaging the semiconductordevice in an encapsulating material to form a packaged semiconductorintegrated circuit device.
 37. The method of claim 36, furthercomprising forming the at least two tape segments to fit within theencapsulating material.
 38. The method of claim 30, wherein the at leasttwo tape segments comprises three or more tape segments.
 39. The methodof claim 30, further including forming at least one aperture in at leastone tape segment of the at least two tape segments.
 40. The method ofclaim 30, wherein the adhesively attaching the at least two tapesegments to the portion of the ends of the plurality of lead fingerscomprises spacing the at least two tape segments to define at least twoopenings between the at least two tape segments.